Median AQI
48
Good
Colorado · County air quality · 2025
Park County, Colorado
Median AQI 48 (Good). 63.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 48
- Median AQI
- 63.0%
- Good-air days
- 0
- Unhealthy days
- 19%
- Cleaner than US counties
Park County's 2025 annual median AQI is 48 (Good), with 63.0% Good days
According to the U.S. EPA Air Quality System, Park County, Colorado posted a 2025 median AQI of 48 (Good) across 203 monitored days, with 63.0% rated Good and 0 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Park County's 63.0% Good-day share places it cleaner than 19% of US counties in 2025.
- Closest median-AQI peer
- Adair County (55.8% Good, median AQI 48) is the closest nationwide median-AQI peer to Park County.
- 2020–2025 trend
- Park County's floor-qualifying Good-day share is improving from 2020 to 2025 (54.5% → 63.1%).
- Median AQI
- Median AQI: 48
The verdict
According to EPA Air Quality System monitoring data, Park County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 48 with 63.0% of 203 monitored days in the Good band, driven mainly by Ozone.
- 48
- median AQI · Good
- 63.0%
- days rated Good
- Ozone
- main pollutant
- 19%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 105.
Annual release change
What changed in the 2025 EPA annual release
- Park County's Good-day share rose from 53.3% to 63.1% between the 2024 and 2025 EPA annual releases, a change of +9.8 percentage points.
- Park County's peak single-day AQI fell from 147 to 105 between the 2024 and 2025 EPA annual releases, a change of -42 points.
Data updated August 2026
- Good · 128 d · 63.1%
- Moderate · 73 d · 36.0%
- USG · 2 d · 1.0%
How did Park County's air break down in 2025?
Across 203 monitored days, 128 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 105 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 203 days monitored. Median AQI: 48 (Good).
Insights: Park County, Colorado. EPA monitors recorded a median Air Quality Index of 48 across 203 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 128 (63%) fell in the Good band (AQI 0–50), 73 (36%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 77, while the worst single-day peak hit 105 (USG). Residents averaged about 18.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (203 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by +8.5 points (measured against 343 monitored days in 2020 and 203 in 2025, so raw day counts are not comparable) and the median AQI moved -2 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 105, usg but never Unhealthy. Nearby counties show comparable readings: Adams (55.1% good, AQI 49); Alamosa (91.5% good, AQI 25); Arapahoe (58.1% good, AQI 48); Archuleta (83.0% good, AQI 34); Boulder (58.4% good, AQI 48); Chaffee (66.0% good, AQI 48).
Air Quality Summary
Good Days
63.0%
128 of 203 monitored days
-12.0pp vs 75% target
Max AQI Recorded
105
USG
Health Grade
Moderate
90th-pct AQI 77
Park County, Good days share 63.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Park County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 203 monitored days across EPA AQI categories.
Good
128
63%
Moderate
73
36%
USG
2
1%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Park County.
- Ozone · 203 days · 100.0%
Health Impact Assessment
Moderate
Park County's air quality is rated Moderate based on 63.0% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 63.0% of monitored days in 2025, with a median AQI of 48. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 203 of 203 monitored days.
5-Year Air Quality Trend
Air quality is improving in Park County. Highest Good-day share: 2022 (65.9%, 172 of 261 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 187 | 146 | 8 | 2 | 50 | 161 |
| 2021 | 203 | 103 | 16 | 0 | 48 | 140 |
| 2022 | 172 | 87 | 1 | 1 | 48 | 190 |
| 2023 | 137 | 129 | 3 | 0 | 50 | 147 |
| 2024 | 172 | 139 | 12 | 0 | 50 | 147 |
| 2025 | 128 | 73 | 2 | 0 | 48 | 105 |
How does Park County compare?
How Park County compares
Good-day share worse than US avg
Park County 63.0%
Adair County, Oklahoma 55.8%
US average 76.0%
Median AQI worse than US avg
Park County 48
Adair County, Oklahoma 48
US average 39
Unhealthy days / yr better than US avg
Park County 0
Adair County, Oklahoma 2
US average 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Park County (48), not geographic neighbors.
Adair County, Oklahoma
Median AQI 48 · 55.8% Good-day share
Arapahoe County, Colorado
Median AQI 48 · 58.1% Good-day share
Arkansas County, Arkansas
Median AQI 48 · 52.9% Good-day share
Ashley County, Arkansas
Median AQI 48 · 55.7% Good-day share
Boulder County, Colorado
Median AQI 48 · 58.4% Good-day share
Bowie County, Texas
Median AQI 48 · 55.0% Good-day share
Same primary pollutant: Ozone
Ozone led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
LaPorte County, Indiana
63.0% Good-day share · median AQI 43
Sutter County, California
63.2% Good-day share · median AQI 47
Davis County, Utah
63.3% Good-day share · median AQI 46
Gila County, Arizona
62.7% Good-day share · median AQI 47
Dewey County, Oklahoma
63.7% Good-day share · median AQI 46
Porter County, Indiana
61.9% Good-day share · median AQI 44
Colorado counties on the map
Geographic containment only, other monitored counties in Colorado, independent of AQI or pollutant match.
What Park County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 48 means for exposure. Health guidance
- See how Park County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Park County with its Colorado neighbours before drawing a conclusion about the region. All of Colorado
Based on 203 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Park County, Colorado? ▼
Park County has a median Air Quality Index (AQI) of 48, rated "Good." 63.0% of monitored days (128 out of 203) had good air quality in 2025.
What is the main pollutant in Park County? ▼
The primary pollutant in Park County is Ozone (O3), which was the main AQI driver on 203 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Park County have? ▼
In 2025, Park County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 105.
Is the air quality in Park County getting better or worse? ▼
Air quality in Park County is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2022 at 65.9% (172 of 261 days). Lowest qualifying Good-day share: 2023 at 50.9% (137 of 269 days).
What does AQI 48 mean for health? ▼
Park County's median AQI of 48 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Park County compare to other counties in Colorado? ▼
Park County has 63.0% good air days. Nearby counties in Colorado: Adams (55.1% good), Alamosa (91.5% good), Arapahoe (58.1% good), Archuleta (83.0% good), Boulder (58.4% good), Chaffee (66.0% good).
What is the 90th percentile AQI in Park County? ▼
The 90th percentile AQI for Park County is 77, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 105 (USG).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Park County, Colorado · 2020–2025
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Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.